dial up 146.90 in your VFO, set the PL to 88.5hz, and your repeater shift to ARS (auto repeater shift) and then save it to memory.

Unless there is an odd-split on the repeater (other than 600hz [.600 Mhz]), you really don't need to worry about the input frequency because modern radios are preset with the band plan and automatically set the input freq, for you.
EDIT: sorry, PL and CTCSS are the same thing. Motorola copyrighted PL (private line) for this sub-audible tone system.

Even though our system is open to all licensed amateurs, we highly encourage everyone who uses the system on a regular basis to become members of GMRA. Members dues help curtail the costs of maintenance and upgrades.

449.100 Mhz 107.2 Hz located on Bald Mesa at 8,500' AMSL near Moab, Utah.
This repeater is the emergeny services backup system when hams support search and resuce and other public safety mutual aid situations. It is linked to the Cactus Net which covers the dez of Utah and Colorado so your QSO will be all over the map.

If you set your CTCSS(PL) to 107.2 Hz you should be able to access the repeater. I would suggest listening to it for a few hours to see what kind of traffic goes on there.